Various techniques have been considered in the field of silver halide photographic light-sensitive materials to improve the covering power of silver halide from the standpoint of conserving silver. Use of tabular silver halide grains is one of these techniques.
The technique of using tabular silver halide grains is excellent with respect to improving the covering power and also has advantages in that the light-receiving area, etc., can be made larger. However, light-sensitive materials using tabular silver halide grains have disadvantages because they are susceptible to changes in development processing conditions and easily fog in high-temperature accelerated processing. Therefore, this technique is not satisfactory for an emulsion having high sensitivity and sufficiently low fog.
Hitherto, it is known to incorporate various additives, such as stabilizers and antifoggants, in ordinary silver halide photographic light-sensitive materials for the purpose of minimizing their dependence on development processing conditions. For example, nitrobenzimidazoles, mercaptothiazoles, benzotriazoles, nitrobenzotriazoles, mercaptotetrazoles, etc., are described as such additives in U.S. Pat. Nos. 3,954,474 and 3,982,947, Japanese Patent Publication No. 28660/77, etc. However, while these additives can depress an increase in fog of a silver halide photographic light-sensitive material containing tabular grains during high-temperature processing to some extent, but a remarkable decrease in sensitivity cannot be prevented.
For example, high-temperature development for efficiently conducting development, particularly, high-temperature accelerated development processing, using an automatic developing machine, is known and is employed in processing of various light-sensitive materials with good results. However, since light-sensitive materials are to be processed at elevated temperatures in this type development processing, photographic emulsion films must be prevented from becoming physically fragile during the processing due to pressure applied thereto by rollers and belts of the automatic developing machine. Therefore, techniques must be worked out to enhance the physical strength of emulsion films during their development in a developing solution so that their physical strength is maintained. For this purpose, one technique involves conducting the processing with an aldehyde hardener to a developing solution. This technique serves to shorten the entire processing time due to the high-temperature processing, and an acceleration of the processing can be attained to some extent. However, development processing with a developing solution containing, for example, an aldehyde, particularly an aliphatic dialdehyde, concurrently causes serious fog formation. This tendency becomes more serious as the temperature of the developing solution increases and as the processing time becomes larger. The fog which occurs with aldehydes can be depressed to some extent by using strong antifogging agents such as benzotriazole and 1-phenyl-5-mercaptotetrazole (as described in L. F. A. Mason, Photographic Processing Chemistry, p. 40, The Forcal Press (1975)). However, these antifogging agents concurrently depress development to a strong extent. Thus, emulsion sensitivity is seriously reduced.
On the other hand, it is known that fog can be depressed effectively by the addition of a dye. For example, U.S. Pat. No. 2,131,038 shows that the alkyl quaternary salt of oxazole, selenazole or thiazole which forms the mother nucleus of the dye depresses fog during high-temperature processing, and U.S. Pat. No. 3,930,860 shows that fog during high-temperature color development can be depressed effectively by the use of a particular dye.
Also, Japanese Patent Application (OPI) No. 61519/79 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") discloses a method for high-temperature development processing using a novel merocyanine dye in combination with high spectral sensitization, and U.S. Pat. No. 4,232,118 discloses a method providing a stable photographic property which causes little fog even in high-temperature processing by using such together with monomethincyanine dye. Moreover, Research Disclosure, January 1983, No. 22534 discloses the use of a particular hemicyanine dye. However, these methods do not provide a satisfactory fog depressing effect when they are employed with tabular silver halide grains having a diameter 5 times or more of their thickness.